Generally, digital paper displays are spotlighted as next generation displays succeeding liquid crystal displays, plasma display panels and electroluminescent devices, and are evaluated as ideally suited to application to reflective displays. In particular, electronic paper is a display capable of displaying letters or images using a flexible substrate such as a thin plastic substrate in which millions of beads are sprayed into oil holes. Electronic paper can be recycled millions of times and is anticipated as a material replacing existing print media, such as books, newspapers, magazines, and the like. Further, electronic paper has much lower production costs than existing flat display panels, and exhibits superior energy efficiency since electronic paper does not require backlighting and continuous recharge as in static screens and thus can be driven even by extremely small energy. Furthermore, since electronic paper is extremely clear, exhibits wide viewing angle and also has a memory function that prevent letters from disappearing when power is not supplied, electronic paper has a possibility of being widely used for public bulletin boards, advertisements, electronic books and the like.
The present invention relates to an adhesive composition for electronic materials or electronic paper. In particular, since an adhesive composition for electronic paper is coated onto an upper side of an ink layer prepared using a highly hydrophobic solvent and is bonded to a protective film through photocuring, the electronic paper can exhibit deterioration in high-temperature reliability and durability due to low compatibility between the solvent and the adhesive composition. Particularly, since the adhesive composition exhibits differences in surface energy and contact angle between before and after photocuring, the adhesive composition cannot provide sufficient adhesion to the protective film.
Although Korean Patent No. 10-1043609 discloses a composition for photocurable adhesive tapes including an acrylic copolymer, a thermal curing agent and a photoinitiator, this composition is aimed at securing good peel strength after UV curing and suffers from reduction in surface energy after UV curing, it is difficult to consider that the document discloses properties allowing contact angle or surface energy to be maintained before and after UV curing.